Emissions system not ready to be tested

Forum Addict

Early in September I went to the dealership because they seem to be the only ones capable of correctly balancing my wheels. While there they offered to do my inspection and I agreed. They came back after a while claiming that the system isn't ready to test and showed me a printout that said that it was reset 0mi ago. My battery was last disconnected 2000mi prior to this (yes, I keep records), I haven't had a single CEL in the years that I've owned this car, so I'm guessing a tech disconnected my battery for some reason. After several weeks and 820mi it still wasn't ready!

I decided to reset the whole system again and disconnected the battery. After a couple of weeks of driving, this morning I followed a drive cycle procedure* I found online and it still says EGR and O2 sensor (not heater, that one is fine) are incomplete. Including the test loop posted above, I've done ~460mi since I reset the battery.

Again, no CELs, car drives fine although I've had some minor idle surges for a while, gas mileage seems normal (maybe 1mpg off but I can't be sure)... What's the deal? Bad cat? Bad O2 sensor? Computer acting up? Already got harassed by a cop with nothing better to do over my rejected inspection sticker.

*I didn't follow it to the T but I did complete each step. After ~15min on the highway I hit traffic and had to slow way down. Made up the two minutes I was going slow for by driving an extra 2-3min at 55mph. Around town GPS put me on a road where I could cruise steady at 45mph so after a few minutes of that I got back on the highway, drove normal (75mph) for 15min, then got onto local roads near my house and drove around for 20min.

The Deported

Which vehicle is this on? Also for most drive cycles, you MUST match conditions exactly or the computer ends it. How old is the battery? Have you done a PID check to see if the temperature sensor is reading accurately (because if it isn't, a lot of things won't happen)?

Also, some I/M systems won't reset if the ambient temperatures are too low when you attempt the drive cycle.

Forum Addict

Brought it to a local garage that I trust. They cleaned out the EGR but O2 and EGR sensor cycles are still incomplete. They ruled out O2 sensors and focused on the unstable idle instead. They determined that the throttle position sensor is ready at 7% open when idle really should be under 2% so the ECU basically never recognizes true idle so the monitors don't run their cycles. They did an idle relearn and it now reads correctly at ~1.7% open at idle but not it's not holding the idle steady. They disconnected the battery for 12hrs and that didn't help either. They're calling in a Honda tech who can "reprogram the idle" with some sort of specialized Honda software but he won't be in until Monday.

For now I got my car back and the idle is doing crazy things. Say I'm rolling up to a stop sign and take it out of gear when it's at 3k rpm - it stays at 3k rpm even though it's in neutral. I have to use the transmission to slow the engine down basically and once it's below 2k or so it falls down to regular idle when it's out of gear. I've never seen anything like this and it makes me miss cable throttles.

On a brighter note, I'm absolutely in love with my TL after driving the loaner car for a week.

The Deported

Unstable idle like that is often traced to a vacuum/boost leak, no matter if it is a cable throttle or drive by wire. On older cars, it can also be traced to a bad idle-up solenoid or idle air controller, or a bad ECU. Worn throttle bodies are also an option. On DBW cars, once vacuum/boost leaks are eliminated as a potential cause, you only have three options - bad throttle body assembly or parts thereof, bad wiring or bad computer.